Cost-benefit analysis of foliar construction and maintenance costs and of carbon assimilation of leaves of differing life-span were conducted using two evergreen, three semi-deciduous, and three deciduous tree species of savannas of north Australia. Rates of radiant-energy-saturated CO2 assimilation (Pmax) and dark respiration were measured and leaves were analysed for total nitrogen, fat, and ash concentrations, and for heat of combustion. Specific leaf area, and leaf N and ash contents were significantly lower in longer-lived leaves (evergreen) than shorter-lived leaves (deciduous) species. Leaves of evergreen species also had significantly higher heat of combustion and lower crude fat content than leaves of deciduous species. On a leaf area basis, Pmax was highest in leaves of evergreen species, but on a leaf dry mass basis it was highest in leaves of deciduous species. Pmax and total Kieldahl N content were linearly correlated across all eight species, and foliar N content was higher in leaves of deciduous than evergreen species. Leaf construction cost was significantly higher and maintenance costs were lower for leaves of evergreen than deciduous species. Maintenance and construction costs were linearly related to each other across all species. Leaves of evergreen species had a higher cost-benefit ratio compared to leaves of deciduous species but with longer lived leaves, the payback interval was longer in evergreen than deciduous species. These results support the hypotheses that longer lived leaves are more expensive to construct than short-lived leaves, and that a higher investment of N into short-lived leaves occurs which supports a higher Pmax over a shorter payback interval. and D. Eamus ... [et al.].
Carbon isotope discrimination (Δ) has been proposed as an indirect estimation criterion for water use efficiency in C3 plants. Because of the higher cost for Δ analysis, ash content or K concentration has been proposed as an alternative criterion for Δ in many species. In five typical habitats of the extreme arid Ejina desert oasis in northwest of China, the seasonal variations of foliar δ, ash content, and potassium (K) concentration were researched in two constructive desert riparian plants (Populus euphratica Olivier, Tamarix ramosissima Ledeb). The correlations of foliar Δ with ash content and K concentration in both species were also examined to evaluate the feasibility of the foliar ash content and K concentration as surrogates of Δ in P. euphratica and T. ramosissima. Results showed that there were significant effects of plant species, habitats and growth season on foliar Δ, ash content, and K concentration. Foliar Δ and K concentration in P. euphratica were significantly higher than those in T. ramosissima, whereas, the ash content was reverse. Among habitats, the trends of δ signatures in both P. euphratica and T. ramosissima were similar, δ values and ash content in both species were the lowest in the dune. Both in the Gobi and dune sites, K concentration in P. euphratica and T. ramosissima was different. In the whole growth period, foliar Δ values and ash content in both species were gradually increased, but K concentration was decreased. Ash content was significantly and positively related to δ in both P. euphratica and T. ramosissima. However, significantly negative correlations between foliar δ and K concentration as well as between ash content and K in P. euphratica were found. In T. ramosissima, the relationship was positive but very weak. and S. K. Cao ... [et al.].
Studie obsahuje nejnovější poznatky o výrobě skla na počátku vrcholného středověku v jednom z nejstarších sklářských výrobních okruhů v Krušných horách, který sestává ze tří skláren situovaných ve vrcholových partiích hor. Jsou v ní prezentovány archeologické prameny získané terénními výzkumy lokalit Jilmová I, II a III. Pozornost je zaměřena na nálezy specifické pro sklářská výrobní centra. Jsou to především zlomky technické keramiky – sklářské pánve, kelímky a odpad doprovázející jednotlivé fáze výroby skla. Klasický typologickomorfologický rozbor doprovází detailní výzkum archeometrický. Výsledky spektrometrických analýz (XRF, XRD, SEM–EDS a LA–ICP–MS) rozšířily výpovědní hodnotu archeologických nálezů a umožnily zpřesnit dosavadní poznatky o technologii výroby skla ve 2. polovině 13. století. and The study contains the latest knowledge concerning glass production at the beginning of the High Middle Ages in one of the oldest glass production areas in the Ore Mountains consisting of three glassworks located in the upper reaches of the mountains. The work presents archaeological sources obtained in excavations at the Jilmová I, II and III sites, with attention being focused on finds specific to glass production centres, i.e., mainly fragments of technical ceramics – melting pots, crucibles and the waste accompanying various stages of glass production. The classic typologicalmorphological analysis is accompanied by a detailed archaeometric analysis. The results of spectrometric analyses (XRF, XRD, SEM–EDS and LA–ICP–MS) expand the informative value of archaeological finds and help refine existing knowledge of glass production technology in the second half of the 13th century.